Main menu width issue

Hi, I am looking after this website for a local group and in some browsers (particularly MS Edge for me, but my client has the issue in Google Chrome, while I do not…), the main menu which has quite a lot of items, is showing as three lines incorrectly, with the middle line being right-justified, and the third line showing “correctly” left-justified. Any suggestions? On the browsers which are “correct”, it just shows as two lines, both left-justified. Thanks in advance.

The page I need help with: [log in to see the link]